ROME — The conclave to select a successor to Pope Benedict XVI is scheduled to begin Tuesday, with cardinals gathering in St. Peter’s Basilica for a morning Mass before the afternoon start of the historic session.

The announcement Friday from the Vatican gave a sudden jolt of momentum to the atmosphere here following days of uncertainty, during which cardinals from around the world trickled in to Rome and began a series of confidential meetings to talk about the future of the church.

A huge platform for television cameras has been erected across from St. Peter’s Square, and news stations from around the world have set up camp on hotel rooftops, their bright lights winking above Bernini’s massive colonnade.

The cardinals are no longer talking to reporters on the record — supposedly because of leaks to the Italian press about the content of the cardinals’ secret talks but perhaps more likely because other cardinals were annoyed by all the attention the media were lavishing on the US cardinals, who were alone in holding on-the-record briefings for the media.

The newspaper La Stampa reported Friday that “Vati-leaks, lack of coordination, problems in the Curia’s relations with bishops’ conferences were all central issues in the cardinals’ speeches during the General Congregation” on Thursday. The paper described a skirmish between two cardinals about the dysfunction in the Vatican bureaucracy.

The accounts in the Italian press are entertaining but impossible to verify. La Stampa described a flurry among Vatican officials to remove bugs secretly planted earlier this year to catch Vatican insiders who leaked confidential papers to the press — lest those listening devices now compromise the secrecy of the conclave.

“A ‘heavy’ apparatus that was useful during the ‘war time’ . . . must now be re-adapted to the extremely delicate ‘peace’ phase during which time the pope is chosen,” the paper said.

Once the conclave begins, the cardinals will move to Domus Sanctae Marthae, a $20 million hotel within the Vatican walls built by John Paul II.

They will be bused between there and the Sistine Chapel, without access to phones, Internet, television, or any other connection to the world until a pope is elected. Staff who assist them take oaths of secrecy.

The Vatican press team showed reporters a video of the interior of Domus Sanctae Marthae, a kind of combination monastery/hotel. Each suite has a bedroom (heavy carved wooden bed frames, white bedspreads, crucifixes hanging overhead) and a small sitting room (desk, phone, upholstered chairs).

Over the weekend, the cardinals will draw lots that determine room assignments, said the Rev. Thomas Rosica, the English language spokesman for the Vatican. Asked whether this was because some rooms were more beautiful than others, he replied that the random drawing simply gave the sense that there were no special favors for anyone.

“Lots are drawn, so everyone is equal,” he said.

The cardinals are also assigned seats during the conclave. But they are allowed to sit wherever they wish in the dining room at mealtime, Rosica said.

The Sistine Chapel has been closed since early Tuesday afternoon to allow for interior construction, including the installation of a raised floor and two heavy wood stoves for the burning of ballots. Chemicals and extra paper are added to help produce the smoke indicating whether or not a pope is elected: black for no, white for yes (though many Vatican observers say it often looks gray). The small chimney will be the focus of TV cameras throughout the conclave.

The Vatican is offering journalists the opportunity to tour the chapel over the weekend while it is under construction.

The 115 prelates voting in the election will also take advantage of the time to meet with one another to discuss the election.

Unlike a vote in, say, an American legislative body, the conclave itself offers little opportunity for debate. Cardinals pray, take oaths of secrecy, cast ballots, and then sit in silent prayer.